The invention relates to a squeeze roller retraction assembly, for use with an electrophotographic copying machine of the type in which a latent image is subjected to a wet developing step and the resulting visual image is transferred onto a record sheet, for facilitating the dismounting or mounting of a photosensitive drum from or onto the machine.
In the known copying process in which an electrostatic latent image is formed on the surface of a photosensitive drum and is converted into a visual image with a developing solution and then the visual image is transfered onto a record sheet, the removal of an excess amount of developing solution which wets the surface of the drum before the visual image is transferred onto the record sheet is essential in order to assure a successful transfer. A squeeze roller is usually employed and is effective to remove such excess amount of developing solution. Referring to FIG. 1 for a brief description of the process involved, there is shown a photosensitive member 1 in the form of a drum, and a squeeze roller 2 is disposed closely thereto at a position intermediate a developing station and a transfer station. The roller 2 is shown as mounted on a rotary shaft 20, which is driven at a rotational speed, determined by the peripheral speed of the drum 1, in a direction which is usually opposite from the direction of rotation of the drum, but which may be the same therewith, in order to remove an excess amount of developing solution from the drum surface. The squeeze roller 2 is urged toward the drum surface, and a pair of bearings 21, 22 rotatably disposed on the opposite ends of the squeeze roller 2 function as spacers to maintain a constant spacing, between the surface 23 of the roller and the drum 1, which corresponds to the difference in diameter between the roller surface 23 and the bearings, by abutting against the opposite ends of the drum surface.
When dismounting or mounting the drum 1 from or onto the copying machine, the squeeze roller 2 must be retracted from the drum surface since otherwise the surface of the drum which is displaced axially may be scratched by the bearings 21, 22 which are maintained in abutting engagement therewith to thereby cause damage to the drum surface or to interfere with the dismounting or mounting operation. Heretofore, the squeeze roller has been retracted by a separate operation from the mounting or withdrawal of the drum, with the result that inadvertent errors have been involved in dismounting the drum without retracting the squeeze roller to cause damage to the drum surface, forgetting to replace the squeeze roller to its operative position after the drum has been mounted, thereby wetting the record sheet too much to provide a good copy.